The present invention relates to a method of manufacturing a glass substrate for a data recording medium, used for a magnetic disk, a magneto-optic disk, or an optical disk, which are a magnetic recording medium for data recording devices such as hard disks.
Conventionally, in order to allow high-density recording in the above described glass substrate for a data recording medium (hereinafter referred to as a “glass substrate”), it is necessary to finish the principal surface on which data is recorded as smooth as possible. For this reason, polishing is applied to smooth the principal surface of the glass substrate using a polishing pad during manufacturing. With regard to this polishing, there is a proposal for a method of manufacturing a glass substrate that improves a micro-waviness value, which is a value representing the smoothness of the principal surface taking advantage of a phenomenon that the value of micro-waviness of a glass substrate depends on the surface roughness of the polishing pad (e.g., see Japanese Laid-Open Patent Application No. 2002-92867). According to this manufacturing method, by selecting a polishing pad with optimal surface roughness to be used for polishing, a glass substrate is manufactured so that micro-waviness on the principal surface reaches a predetermined value.
However, according to the conventional method described above, even if a polishing pad with good surface roughness is selected, micro-waviness may not reach the predetermined value during polishing. Since a micro-waviness value of a glass substrate depends on the value of surface roughness of the polishing pad, the fact that the micro-waviness value does not reach a predetermined value may be attributable to occasional roughness of the surface of the polishing pad during polishing. For this reason, it cannot always be determined that selecting a polishing pad with optimal surface roughness allows manufacturing of a glass substrate having a principal surface with desired micro-waviness.